Electrochemical Detection And Adsorptive Removal Of Thiocyanate

In this thesis, a multiwall nanotube composite modified electrode was used to detect electrochemical response of thiocyanate. AgCl nanoparticles-loaded hydrotalcite was prepared, which was used as adsorbent to remove thiocyanate from contaminated water. The main work was described as follows:The electrochemical response of different modified electrodes such as glass carbon electrode (GCE), chitosan-multiwall carbon nanotube composite modified glass carbon electrode (CHI-CNTs/GCE), poly diallyldimethylammonium chloride-multiwall carbon nanotube composite modified glass carbon electrode (PDDA-CNTs/GCE) and cetyltrimethylammonium bromide--multiwall carbon nanotube composite modified glass carbon electrode (CTAB-CNTs/GCE), toward thiocyanate were compared. The results showed that the electrochemical response of CTAB-CNTs/GCE towards thiocyanate had a great improvement, with the oxidation peak potential shifting to more negative. The reaction between the CTAB-CNTs/GCE and thiocyanate was investigated under optimum condition. In the pH2.0suppotring electrolyte of hydrochloric acid,10μL of CTAB-CNTs modifier,120s of preconcentration time, the electrochemical response versus the concentration of thiocyanate showed a well linear ship. The peak current was linearly increasd with increasing the concentration of thiocyanate from5.0×10-6to1.0×10-4mol·L-1and linear equation was expressed as ip (μA)=-0.75381+4.70×105c (mol·L-1), with the detection limit was3.0×10-6mol·L-1.Hydrotalcite, a kind of anionic clays, was prepared by conventional co-precipitation method. Silver chloride nanoparticles loaded on this layered double hydrotalcite were also synthesized. The as prepared AgCl/LDH and LDH were characterized with scanning electron microscopy (SEM), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results indicated that AgCl nanoparticles were loaded on LDH. The adsorption removal for thiocyanate was investigated using AgCl/LDH as adsorbent. It is clearly demonstrated that the loading of AgCl nanoparticles remarkably improved the adsorptive removal efficiency of LDH for thiocyanate. The influencing factors such as temperature, adsorbent dosage, silver content and initial thiocyanate concentration were systematically investigated. The maximum adsorption capacity of AgCl/LDH for thiocyanate reached108.6mg·g-1under optimum conditions. The mechanism for the promotion of AgCl/LDH to the adsorptive removal of thiocyanate was analyzed by fourier transform infrared spectrometer and X-ray diffraction.